According to css-grid-2, the last step of the track sizing algo is to stretch auto tracks.

In css-grid-3 is a tentative definition for sizing auto tracks within an auto repeat. In addition to the rules provided, I think we will want to suppress stretching of auto sized tracks during the auto track sizing pass to avoid ending up with one auto repeat track filling the entire available space.

Perhaps it is implied, but may be worth spelling it out as one of the listed differences for clarity.

CC @tabatkins @bfgeek